Casepetries Electronics Structuring Systems Requirements

Casepetries Electronicsstructuring Systems Requirementsconceptual D

Review the DFDs and identify attributes of each entity, provide definitions, redraw the ER diagram with attributes, select identifiers, draw relationships with cardinalities, and justify your choices.

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Analysis of System Requirements and Data Modeling for Petrie’s Electronics Customer Loyalty Program

The development of a comprehensive data model for Petrie’s Electronics' customer loyalty system requires a thorough understanding of the entities involved, their attributes, and the relationships that connect them. The goal is to create an unambiguous, well-structured Entity-Relationship (ER) diagram that accurately captures the business rules and supports the system's data needs.

Identification and Attribute Definition of Entities

The initial step involves extracting entities from the provided descriptions, particularly focusing on entity descriptions and classifying attributes. The primary entities identified from the case include Customer, Coupon, Product, Promotion, Service, and Transaction. Occasionally, additional entities may emerge based on the transactional interactions or system requirements.

Customer

  • CustomerID: A unique identifier assigned to each customer; used as the primary key.
  • Name: The full name of the customer.
  • Email: Contact email address.
  • PhoneNumber: Contact phone number.
  • Address: Physical mailing address.
  • MembershipLevel: Indicates the loyalty tier of the customer (e.g., Gold, Silver).

The CustomerID serves as an essential identifier because it uniquely differentiates each customer's data record in the system.

Coupon

  • CouponID: A unique code for each coupon.
  • Value: The dollar amount the coupon is worth.
  • RedemptionPoints: The number of loyalty points required for creation.
  • CreationDate: Date when the coupon was issued.
  • ExpiryDate: Validity period end date.
  • CustomerID: Links each coupon to its associated customer.

Coupon identification via CouponID ensures each coupon's uniqueness, facilitating accurate tracking during redemption and accounting processes.

Product

  • ProductID: Unique identifier for each product.
  • Name: Product name.
  • Description: Brief product details.
  • Price: Sale price of the product.
  • Category: Product classification (e.g., Electronics, Accessories).

The ProductID is crucial for distinguishing each product in sales and promotional contexts.

Promotion

  • PromotionID: Unique promotion code.
  • Type: Description of promotion type (e.g., 2-for-1).
  • Description: Details about the promotion.
  • StartDate: Promotion start date.
  • EndDate: Promotion expiry date.

Service

  • ServiceID: Unique identifier for each job performed.
  • Description: Details of the service performed.
  • ServiceDate: Date when the service was performed.
  • CustomerID: The customer for whom the service was performed.
  • Price: Cost of performing the service.

Transaction

  • TransactionID: Unique transaction identifier.
  • Date: Date of transaction.
  • CustomerID: Customer involved in the transaction.
  • TotalAmount: Total dollar value of the transaction.
  • PointsEarned: Loyalty points earned for the transaction.

Redrawing the ER Diagram with Entities and Attributes

Using the identified entities and their attributes, the ER diagram consolidates these components visually. Each entity is represented as a rectangle, with attributes listed within or connected to their entities. The primary key attributes are underlined to denote their unique identification role.

The diagram contains the six core entities along with their attributes, connected via relationships based on their business interactions. For example, Customer has a one-to-many relationship with Transaction, as each customer can have multiple transactions. Coupons are associated with Customers through a "Has" relationship, indicating loyalty benefits.

Entity Identifiers and Justification

Identifiers are selected based on their ability to uniquely differentiate each entity instance:

  • Customer: CustomerID — unique customer identifier, essential for customer-specific data.
  • Coupon: CouponID — ensures each coupon can be distinctly tracked from creation to redemption.
  • Product: ProductID — distinguishes products in inventory and sales records.
  • Promotion: PromotionID — identifies promotional campaigns uniquely.
  • Service: ServiceID — differentiates each service performed for a customer.
  • Transaction: TransactionID — uniquely records each purchase or transaction event.

The choice of these identifiers is grounded in their necessity for maintaining data integrity, enabling effective retrieval, and supporting key business processes.

Relationships and Cardinalities

Establishing meaningful relationships involves examining how entities interact within the business operations:

  • Customer-Transaction: A customer can have numerous transactions; the relationship is one-to-many (1:N). The minimum is one if every customer must perform at least one transaction; otherwise, it can be zero. The maximum aligns with the number of transactions a customer can perform.
  • Customer-Coupon: A customer may hold multiple coupons; a coupon belongs to only one customer (1:N). Here, the minimum is zero for customers without coupons, and maximum depends on how many coupons a customer can hold.
  • Transaction-Product: A transaction can involve multiple products, and each product can be part of multiple transactions, indicating a many-to-many (M:N) relationship, requiring an associative entity or relationship node.
  • Promotion-Product: Promotions may target multiple products, and each product can be associated with multiple promotions, also a many-to-many relationship.
  • Service-Customer: Each service performed is linked to a single customer, forming a one-to-many (1:N) relationship.

Cardinalities are chosen based on business rules; for example, a single transaction can contain multiple products, but each product within that transaction relates back to only one transaction.

Final ER Diagram Construction

The final ER diagram is constructed visually using tools like Microsoft Visio, positioning entities logically with attributes and relationships clearly labeled. The diagram emphasizes clarity, concise relationships, and correct cardinalities, supporting the development of an efficient database schema for the loyalty system.

Conclusion

Developing an unambiguous, comprehensive data model for Petrie’s Electronics entails careful extraction of entity attributes, choosing appropriate identifiers, and establishing well-justified relationships with accurate cardinalities. This systematic approach ensures that the database designed from the ER diagram will accurately mirror business processes, facilitate data integrity, and support the company's strategic goals for its customer loyalty program.

References

  • Elmasri, R., & Navathe, S. B. (2015). Fundamentals of Database Systems. Pearson.

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